rgb_led_ws281x: rework the .decode() main loop, improve robustness

[libsigrokdecode/gsi.git] / instance.c

/*
 * This file is part of the libsigrokdecode project.
 *
 * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
#include "libsigrokdecode.h"
#include <glib.h>
#include <inttypes.h>
#include <stdlib.h>
#include <stdint.h>

/** @cond PRIVATE */

extern SRD_PRIV GSList *sessions;

/** @endcond */

/**
 * @file
 *
 * Decoder instance handling.
 */

/**
 * @defgroup grp_instances Decoder instances
 *
 * Decoder instance handling.
 *
 * @{
 */

static void oldpins_array_seed(struct srd_decoder_inst *di)
{
        size_t count;
        GArray *arr;

        if (!di)
                return;
        if (di->old_pins_array)
                return;

        count = di->dec_num_channels;
        arr = g_array_sized_new(FALSE, TRUE, sizeof(uint8_t), count);
        g_array_set_size(arr, count);
        if (arr->data)
                memset(arr->data, SRD_INITIAL_PIN_SAME_AS_SAMPLE0, count);
        di->old_pins_array = arr;
}

static void oldpins_array_free(struct srd_decoder_inst *di)
{
        if (!di)
                return;
        if (!di->old_pins_array)
                return;

        srd_dbg("%s: Releasing initial pin state.", di->inst_id);

        g_array_free(di->old_pins_array, TRUE);
        di->old_pins_array = NULL;
}

/**
 * Set one or more options in a decoder instance.
 *
 * Handled options are removed from the hash.
 *
 * @param di Decoder instance.
 * @param options A GHashTable of options to set.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
                GHashTable *options)
{
        struct srd_decoder_option *sdo;
        PyObject *py_di_options, *py_optval;
        GVariant *value;
        GSList *l;
        double val_double;
        gint64 val_int;
        int ret;
        const char *val_str;
        PyGILState_STATE gstate;

        if (!di) {
                srd_err("Invalid decoder instance.");
                return SRD_ERR_ARG;
        }

        if (!options) {
                srd_err("Invalid options GHashTable.");
                return SRD_ERR_ARG;
        }

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(di->decoder->py_dec, "options")) {
                /* Decoder has no options. */
                PyGILState_Release(gstate);
                if (g_hash_table_size(options) == 0) {
                        /* No options provided. */
                        return SRD_OK;
                } else {
                        srd_err("Protocol decoder has no options.");
                        return SRD_ERR_ARG;
                }
                return SRD_OK;
        }

        ret = SRD_ERR_PYTHON;
        py_optval = NULL;

        /*
         * The 'options' tuple is a class variable, but we need to
         * change it. Changing it directly will affect the entire class,
         * so we need to create a new object for it, and populate that
         * instead.
         */
        if (!(py_di_options = PyObject_GetAttrString(di->py_inst, "options")))
                goto err_out;
        Py_DECREF(py_di_options);
        py_di_options = PyDict_New();
        PyObject_SetAttrString(di->py_inst, "options", py_di_options);
        Py_DECREF(py_di_options);

        for (l = di->decoder->options; l; l = l->next) {
                sdo = l->data;
                if ((value = g_hash_table_lookup(options, sdo->id))) {
                        /* A value was supplied for this option. */
                        if (!g_variant_type_equal(g_variant_get_type(value),
                                  g_variant_get_type(sdo->def))) {
                                srd_err("Option '%s' should have the same type "
                                        "as the default value.", sdo->id);
                                goto err_out;
                        }
                } else {
                        /* Use default for this option. */
                        value = sdo->def;
                }
                if (g_variant_is_of_type(value, G_VARIANT_TYPE_STRING)) {
                        val_str = g_variant_get_string(value, NULL);
                        if (!(py_optval = PyUnicode_FromString(val_str))) {
                                /* Some UTF-8 encoding error. */
                                PyErr_Clear();
                                srd_err("Option '%s' requires a UTF-8 string value.", sdo->id);
                                goto err_out;
                        }
                } else if (g_variant_is_of_type(value, G_VARIANT_TYPE_INT64)) {
                        val_int = g_variant_get_int64(value);
                        if (!(py_optval = PyLong_FromLongLong(val_int))) {
                                /* ValueError Exception */
                                PyErr_Clear();
                                srd_err("Option '%s' has invalid integer value.", sdo->id);
                                goto err_out;
                        }
                } else if (g_variant_is_of_type(value, G_VARIANT_TYPE_DOUBLE)) {
                        val_double = g_variant_get_double(value);
                        if (!(py_optval = PyFloat_FromDouble(val_double))) {
                                /* ValueError Exception */
                                PyErr_Clear();
                                srd_err("Option '%s' has invalid float value.",
                                        sdo->id);
                                goto err_out;
                        }
                }
                if (PyDict_SetItemString(py_di_options, sdo->id, py_optval) == -1) {
                        Py_XDECREF(py_optval);
                        goto err_out;
                }
                /* Not harmful even if we used the default. */
                g_hash_table_remove(options, sdo->id);
                Py_XDECREF(py_optval);
        }
        if (g_hash_table_size(options) != 0)
                srd_warn("Unknown options specified for '%s'", di->inst_id);

        ret = SRD_OK;

err_out:
        if (PyErr_Occurred()) {
                srd_exception_catch("Stray exception in srd_inst_option_set()");
                ret = SRD_ERR_PYTHON;
        }
        PyGILState_Release(gstate);

        return ret;
}

/* Helper GComparefunc for g_slist_find_custom() in srd_inst_channel_set_all(). */
static gint compare_channel_id(const struct srd_channel *pdch,
                        const char *channel_id)
{
        return strcmp(pdch->id, channel_id);
}

/**
 * Set all channels in a decoder instance.
 *
 * This function sets _all_ channels for the specified decoder instance, i.e.,
 * it overwrites any channels that were already defined (if any).
 *
 * @param di Decoder instance.
 * @param new_channels A GHashTable of channels to set. Key is channel name,
 *                     value is the channel number. Samples passed to this
 *                     instance will be arranged in this order.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.4.0
 */
SRD_API int srd_inst_channel_set_all(struct srd_decoder_inst *di,
                GHashTable *new_channels)
{
        GVariant *channel_val;
        GList *l;
        GSList *sl;
        struct srd_channel *pdch;
        int *new_channelmap, new_channelnum, num_required_channels, i;
        char *channel_id;

        srd_dbg("Setting channels for instance %s with list of %d channels.",
                di->inst_id, g_hash_table_size(new_channels));

        if (g_hash_table_size(new_channels) == 0)
                /* No channels provided. */
                return SRD_OK;

        if (di->dec_num_channels == 0) {
                /* Decoder has no channels. */
                srd_err("Protocol decoder %s has no channels to define.",
                        di->decoder->name);
                return SRD_ERR_ARG;
        }

        new_channelmap = g_malloc0(sizeof(int) * di->dec_num_channels);

        /*
         * For now, map all indexes to channel -1 (can be overridden later).
         * This -1 is interpreted as an unspecified channel later.
         */
        for (i = 0; i < di->dec_num_channels; i++)
                new_channelmap[i] = -1;

        for (l = g_hash_table_get_keys(new_channels); l; l = l->next) {
                channel_id = l->data;
                channel_val = g_hash_table_lookup(new_channels, channel_id);
                if (!g_variant_is_of_type(channel_val, G_VARIANT_TYPE_INT32)) {
                        /* Channel name was specified without a value. */
                        srd_err("No channel number was specified for %s.",
                                        channel_id);
                        g_free(new_channelmap);
                        return SRD_ERR_ARG;
                }
                new_channelnum = g_variant_get_int32(channel_val);
                if (!(sl = g_slist_find_custom(di->decoder->channels, channel_id,
                                (GCompareFunc)compare_channel_id))) {
                        /* Fall back on optional channels. */
                        if (!(sl = g_slist_find_custom(di->decoder->opt_channels,
                             channel_id, (GCompareFunc)compare_channel_id))) {
                                srd_err("Protocol decoder %s has no channel "
                                        "'%s'.", di->decoder->name, channel_id);
                                g_free(new_channelmap);
                                return SRD_ERR_ARG;
                        }
                }
                pdch = sl->data;
                new_channelmap[pdch->order] = new_channelnum;
                srd_dbg("Setting channel mapping: %s (PD ch idx %d) = input data ch idx %d.",
                        pdch->id, pdch->order, new_channelnum);
        }

        srd_dbg("Final channel map:");
        num_required_channels = g_slist_length(di->decoder->channels);
        for (i = 0; i < di->dec_num_channels; i++) {
                GSList *ll = g_slist_nth(di->decoder->channels, i);
                if (!ll)
                        ll = g_slist_nth(di->decoder->opt_channels,
                                i - num_required_channels);
                pdch = ll->data;
                srd_dbg(" - PD ch idx %d (%s) = input data ch idx %d (%s)", i,
                        pdch->id, new_channelmap[i],
                        (i < num_required_channels) ? "required" : "optional");
        }

        /* Report an error if not all required channels were specified. */
        for (i = 0; i < num_required_channels; i++) {
                if (new_channelmap[i] != -1)
                        continue;
                pdch = g_slist_nth(di->decoder->channels, i)->data;
                srd_err("Required channel '%s' (index %d) was not specified.",
                        pdch->id, i);
                g_free(new_channelmap);
                return SRD_ERR;
        }

        g_free(di->dec_channelmap);
        di->dec_channelmap = new_channelmap;

        return SRD_OK;
}

/**
 * Create a new protocol decoder instance.
 *
 * @param sess The session holding the protocol decoder instance.
 *             Must not be NULL.
 * @param decoder_id Decoder 'id' field.
 * @param options GHashtable of options which override the defaults set in
 *                the decoder class. May be NULL.
 *
 * @return Pointer to a newly allocated struct srd_decoder_inst, or
 *         NULL in case of failure.
 *
 * @since 0.3.0
 */
SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
                const char *decoder_id, GHashTable *options)
{
        int i;
        struct srd_decoder *dec;
        struct srd_decoder_inst *di;
        char *inst_id;
        PyGILState_STATE gstate;

        i = 1;

        if (!sess)
                return NULL;

        if (!(dec = srd_decoder_get_by_id(decoder_id))) {
                srd_err("Protocol decoder %s not found.", decoder_id);
                return NULL;
        }

        di = g_malloc0(sizeof(struct srd_decoder_inst));

        di->decoder = dec;
        di->sess = sess;

        if (options) {
                inst_id = g_hash_table_lookup(options, "id");
                if (inst_id)
                        di->inst_id = g_strdup(inst_id);
                g_hash_table_remove(options, "id");
        }

        /* Create a unique instance ID (as none was provided). */
        if (!di->inst_id) {
                di->inst_id = g_strdup_printf("%s-%d", decoder_id, i++);
                while (srd_inst_find_by_id(sess, di->inst_id)) {
                        g_free(di->inst_id);
                        di->inst_id = g_strdup_printf("%s-%d", decoder_id, i++);
                }
        }

        /*
         * Prepare a default channel map, where samples come in the
         * order in which the decoder class defined them.
         */
        di->dec_num_channels = g_slist_length(di->decoder->channels) +
                        g_slist_length(di->decoder->opt_channels);
        if (di->dec_num_channels) {
                di->dec_channelmap =
                                g_malloc(sizeof(int) * di->dec_num_channels);
                for (i = 0; i < di->dec_num_channels; i++)
                        di->dec_channelmap[i] = i;
                /*
                 * Will be used to prepare a sample at every iteration
                 * of the instance's decode() method.
                 */
                di->channel_samples = g_malloc(di->dec_num_channels);
        }

        /* Default to the initial pins being the same as in sample 0. */
        oldpins_array_seed(di);

        gstate = PyGILState_Ensure();

        /* Create a new instance of this decoder class. */
        if (!(di->py_inst = PyObject_CallObject(dec->py_dec, NULL))) {
                if (PyErr_Occurred())
                        srd_exception_catch("Failed to create %s instance",
                                        decoder_id);
                PyGILState_Release(gstate);
                g_free(di->dec_channelmap);
                g_free(di);
                return NULL;
        }

        PyGILState_Release(gstate);

        if (options && srd_inst_option_set(di, options) != SRD_OK) {
                g_free(di->dec_channelmap);
                g_free(di);
                return NULL;
        }

        di->condition_list = NULL;
        di->match_array = NULL;
        di->abs_start_samplenum = 0;
        di->abs_end_samplenum = 0;
        di->inbuf = NULL;
        di->inbuflen = 0;
        di->abs_cur_samplenum = 0;
        di->thread_handle = NULL;
        di->got_new_samples = FALSE;
        di->handled_all_samples = FALSE;
        di->want_wait_terminate = FALSE;
        di->communicate_eof = FALSE;
        di->decoder_state = SRD_OK;

        /*
         * Strictly speaking initialization of statically allocated
         * condition and mutex variables (or variables allocated on the
         * stack) is not required, but won't harm either. Explicitly
         * running init() will better match subsequent clear() calls.
         */
        g_cond_init(&di->got_new_samples_cond);
        g_cond_init(&di->handled_all_samples_cond);
        g_mutex_init(&di->data_mutex);

        /* Instance takes input from a frontend by default. */
        sess->di_list = g_slist_append(sess->di_list, di);
        srd_dbg("Creating new %s instance %s.", decoder_id, di->inst_id);

        return di;
}

static void srd_inst_join_decode_thread(struct srd_decoder_inst *di)
{
        if (!di)
                return;
        if (!di->thread_handle)
                return;

        srd_dbg("%s: Joining decoder thread.", di->inst_id);

        /*
         * Terminate potentially running threads which still
         * execute the decoder instance's decode() method.
         */
        srd_dbg("%s: Raising want_term, sending got_new.", di->inst_id);
        g_mutex_lock(&di->data_mutex);
        di->want_wait_terminate = TRUE;
        g_cond_signal(&di->got_new_samples_cond);
        g_mutex_unlock(&di->data_mutex);

        srd_dbg("%s: Running join().", di->inst_id);
        (void)g_thread_join(di->thread_handle);
        srd_dbg("%s: Call to join() done.", di->inst_id);
        di->thread_handle = NULL;

        /*
         * Reset condition and mutex variables, such that next
         * operations on them will find them in a clean state.
         */
        g_cond_clear(&di->got_new_samples_cond);
        g_cond_init(&di->got_new_samples_cond);
        g_cond_clear(&di->handled_all_samples_cond);
        g_cond_init(&di->handled_all_samples_cond);
        g_mutex_clear(&di->data_mutex);
        g_mutex_init(&di->data_mutex);
}

static void srd_inst_reset_state(struct srd_decoder_inst *di)
{
        if (!di)
                return;

        srd_dbg("%s: Resetting decoder state.", di->inst_id);

        /* Reset internal state of the decoder. */
        condition_list_free(di);
        match_array_free(di);
        di->abs_start_samplenum = 0;
        di->abs_end_samplenum = 0;
        di->inbuf = NULL;
        di->inbuflen = 0;
        di->abs_cur_samplenum = 0;
        oldpins_array_free(di);
        di->got_new_samples = FALSE;
        di->handled_all_samples = FALSE;
        di->want_wait_terminate = FALSE;
        di->communicate_eof = FALSE;
        di->decoder_state = SRD_OK;
        /* Conditions and mutex got reset after joining the thread. */
}

/**
 * Stack a decoder instance on top of another.
 *
 * @param sess The session holding the protocol decoder instances.
 *             Must not be NULL.
 * @param di_bottom The instance on top of which di_top will be stacked.
 * @param di_top The instance to go on top.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.3.0
 */
SRD_API int srd_inst_stack(struct srd_session *sess,
                struct srd_decoder_inst *di_bottom,
                struct srd_decoder_inst *di_top)
{
        if (!sess)
                return SRD_ERR_ARG;

        if (!di_bottom || !di_top) {
                srd_err("Invalid from/to instance pair.");
                return SRD_ERR_ARG;
        }

        if (g_slist_find(sess->di_list, di_top)) {
                /* Remove from the unstacked list. */
                sess->di_list = g_slist_remove(sess->di_list, di_top);
        }

        /*
         * Check if there's at least one matching input/output pair
         * for the stacked PDs. We warn if that's not the case, but it's
         * not a hard error for the time being.
         */
        gboolean at_least_one_match = FALSE;
        for (GSList *out = di_bottom->decoder->outputs; out; out = out->next) {
                const char *o = out->data;
                for (GSList *in = di_top->decoder->inputs; in; in = in->next) {
                        const char *i = in->data;
                        if (!strcmp(o, i)) {
                                at_least_one_match = TRUE;
                                break;
                        }
                }
        }

        if (!at_least_one_match)
                srd_warn("No matching in-/output when stacking %s onto %s.",
                        di_top->inst_id, di_bottom->inst_id);

        /* Stack on top of source di. */
        di_bottom->next_di = g_slist_append(di_bottom->next_di, di_top);

        srd_dbg("Stacking %s onto %s.", di_top->inst_id, di_bottom->inst_id);

        return SRD_OK;
}

/**
 * Search a decoder instance and its stack for instance ID.
 *
 * @param[in] inst_id ID to search for.
 * @param[in] stack A decoder instance, potentially with stacked instances.
 *
 * @return The matching instance, or NULL.
 */
static struct srd_decoder_inst *srd_inst_find_by_id_stack(const char *inst_id,
                struct srd_decoder_inst *stack)
{
        const GSList *l;
        struct srd_decoder_inst *tmp, *di;

        if (!strcmp(stack->inst_id, inst_id))
                return stack;

        /* Otherwise, look recursively in our stack. */
        di = NULL;
        if (stack->next_di) {
                for (l = stack->next_di; l; l = l->next) {
                        tmp = l->data;
                        if (!strcmp(tmp->inst_id, inst_id)) {
                                di = tmp;
                                break;
                        }
                }
        }

        return di;
}

/**
 * Find a decoder instance by its instance ID.
 *
 * This will recurse to find the instance anywhere in the stack tree of the
 * given session.
 *
 * @param sess The session holding the protocol decoder instance.
 *             Must not be NULL.
 * @param inst_id The instance ID to be found.
 *
 * @return Pointer to struct srd_decoder_inst, or NULL if not found.
 *
 * @since 0.3.0
 */
SRD_API struct srd_decoder_inst *srd_inst_find_by_id(struct srd_session *sess,
                const char *inst_id)
{
        GSList *l;
        struct srd_decoder_inst *tmp, *di;

        if (!sess)
                return NULL;

        di = NULL;
        for (l = sess->di_list; l; l = l->next) {
                tmp = l->data;
                if ((di = srd_inst_find_by_id_stack(inst_id, tmp)) != NULL)
                        break;
        }

        return di;
}

/**
 * Set the list of initial (assumed) pin values.
 *
 * @param di Decoder instance to use. Must not be NULL.
 * @param initial_pins A GArray of uint8_t values. Must not be NULL.
 *
 * @since 0.5.0
 */
SRD_API int srd_inst_initial_pins_set_all(struct srd_decoder_inst *di, GArray *initial_pins)
{
        int i;
        GString *s;

        if (!di) {
                srd_err("Invalid decoder instance.");
                return SRD_ERR_ARG;
        }

        if (!initial_pins)
                return SRD_ERR_ARG;

        if (initial_pins->len != (guint)di->dec_num_channels) {
                srd_err("Incorrect number of channels (need %d, got %d).",
                        di->dec_num_channels, initial_pins->len);
                return SRD_ERR_ARG;
        }

        /* Sanity-check initial pin state values. */
        for (i = 0; i < di->dec_num_channels; i++) {
                if (initial_pins->data[i] <= 2)
                        continue;
                srd_err("Invalid initial channel %d pin state: %d.",
                        i, initial_pins->data[i]);
                return SRD_ERR_ARG;
        }

        s = g_string_sized_new(100);
        oldpins_array_seed(di);
        for (i = 0; i < di->dec_num_channels; i++) {
                di->old_pins_array->data[i] = initial_pins->data[i];
                g_string_append_printf(s, "%d, ", di->old_pins_array->data[i]);
        }
        s = g_string_truncate(s, s->len - 2);
        srd_dbg("Initial pins: %s.", s->str);
        g_string_free(s, TRUE);

        return SRD_OK;
}

/** @private */
SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
{
        PyObject *py_res, *py_samplenum;
        GSList *l;
        struct srd_decoder_inst *next_di;
        int ret;
        PyGILState_STATE gstate;

        srd_dbg("Calling start() of instance %s.", di->inst_id);

        gstate = PyGILState_Ensure();

        /* Run self.start(). */
        if (!(py_res = PyObject_CallMethod(di->py_inst, "start", NULL))) {
                srd_exception_catch("Protocol decoder instance %s",
                                di->inst_id);
                PyGILState_Release(gstate);
                return SRD_ERR_PYTHON;
        }
        Py_DECREF(py_res);

        /* Set self.samplenum to 0. */
        py_samplenum = PyLong_FromUnsignedLongLong(0);
        PyObject_SetAttrString(di->py_inst, "samplenum", py_samplenum);
        Py_DECREF(py_samplenum);

        /* Set self.matched to None. */
        PyObject_SetAttrString(di->py_inst, "matched", Py_None);

        PyGILState_Release(gstate);

        /* Start all the PDs stacked on top of this one. */
        for (l = di->next_di; l; l = l->next) {
                next_di = l->data;
                if ((ret = srd_inst_start(next_di)) != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Check whether the specified sample matches the specified term.
 *
 * In the case of SRD_TERM_SKIP, this function can modify
 * term->num_samples_already_skipped.
 *
 * @param old_sample The value of the previous sample (0/1).
 * @param sample The value of the current sample (0/1).
 * @param term The term that should be checked for a match. Must not be NULL.
 *
 * @retval TRUE The current sample matches the specified term.
 * @retval FALSE The current sample doesn't match the specified term, or an
 *               invalid term was provided.
 *
 * @private
 */
__attribute__((always_inline))
static inline gboolean sample_matches(uint8_t old_sample, uint8_t sample, struct srd_term *term)
{
        /* Caller ensures term != NULL. */

        switch (term->type) {
        case SRD_TERM_HIGH:
                if (sample == 1)
                        return TRUE;
                break;
        case SRD_TERM_LOW:
                if (sample == 0)
                        return TRUE;
                break;
        case SRD_TERM_RISING_EDGE:
                if (old_sample == 0 && sample == 1)
                        return TRUE;
                break;
        case SRD_TERM_FALLING_EDGE:
                if (old_sample == 1 && sample == 0)
                        return TRUE;
                break;
        case SRD_TERM_EITHER_EDGE:
                if ((old_sample == 1 && sample == 0) || (old_sample == 0 && sample == 1))
                        return TRUE;
                break;
        case SRD_TERM_NO_EDGE:
                if ((old_sample == 0 && sample == 0) || (old_sample == 1 && sample == 1))
                        return TRUE;
                break;
        case SRD_TERM_SKIP:
                if (term->num_samples_already_skipped == term->num_samples_to_skip)
                        return TRUE;
                term->num_samples_already_skipped++;
                break;
        default:
                srd_err("Unknown term type %d.", term->type);
                break;
        }

        return FALSE;
}

/** @private */
SRD_PRIV void match_array_free(struct srd_decoder_inst *di)
{
        if (!di || !di->match_array)
                return;

        g_array_free(di->match_array, TRUE);
        di->match_array = NULL;
}

/** @private */
SRD_PRIV void condition_list_free(struct srd_decoder_inst *di)
{
        GSList *l, *ll;

        if (!di)
                return;

        for (l = di->condition_list; l; l = l->next) {
                ll = l->data;
                if (ll)
                        g_slist_free_full(ll, g_free);
        }

        g_slist_free(di->condition_list);
        di->condition_list = NULL;
}

static gboolean have_non_null_conds(const struct srd_decoder_inst *di)
{
        GSList *l, *cond;

        if (!di)
                return FALSE;

        for (l = di->condition_list; l; l = l->next) {
                cond = l->data;
                if (cond)
                        return TRUE;
        }

        return FALSE;
}

static void update_old_pins_array(struct srd_decoder_inst *di,
                const uint8_t *sample_pos)
{
        uint8_t sample;
        int i, byte_offset, bit_offset;

        if (!di || !di->dec_channelmap || !sample_pos)
                return;

        oldpins_array_seed(di);
        for (i = 0; i < di->dec_num_channels; i++) {
                if (di->dec_channelmap[i] == -1)
                        continue; /* Ignore unused optional channels. */
                byte_offset = di->dec_channelmap[i] / 8;
                bit_offset = di->dec_channelmap[i] % 8;
                sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
                di->old_pins_array->data[i] = sample;
        }
}

static void update_old_pins_array_initial_pins(struct srd_decoder_inst *di)
{
        uint8_t sample;
        int i, byte_offset, bit_offset;
        const uint8_t *sample_pos;

        if (!di || !di->dec_channelmap)
                return;

        sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);

        oldpins_array_seed(di);
        for (i = 0; i < di->dec_num_channels; i++) {
                if (di->old_pins_array->data[i] != SRD_INITIAL_PIN_SAME_AS_SAMPLE0)
                        continue;
                if (di->dec_channelmap[i] == -1)
                        continue; /* Ignore unused optional channels. */
                byte_offset = di->dec_channelmap[i] / 8;
                bit_offset = di->dec_channelmap[i] % 8;
                sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
                di->old_pins_array->data[i] = sample;
        }
}

static gboolean term_matches(const struct srd_decoder_inst *di,
                struct srd_term *term, const uint8_t *sample_pos)
{
        uint8_t old_sample, sample;
        int byte_offset, bit_offset, ch;

        /* Caller ensures di, di->dec_channelmap, term, sample_pos != NULL. */

        if (term->type == SRD_TERM_SKIP)
                return sample_matches(0, 0, term);

        ch = term->channel;
        byte_offset = di->dec_channelmap[ch] / 8;
        bit_offset = di->dec_channelmap[ch] % 8;
        sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
        old_sample = di->old_pins_array->data[ch];

        return sample_matches(old_sample, sample, term);
}

static gboolean all_terms_match(const struct srd_decoder_inst *di,
                const GSList *cond, const uint8_t *sample_pos)
{
        const GSList *l;
        struct srd_term *term;

        /* Caller ensures di, cond, sample_pos != NULL. */

        for (l = cond; l; l = l->next) {
                term = l->data;
                if (term->type == SRD_TERM_ALWAYS_FALSE)
                        return FALSE;
                if (!term_matches(di, term, sample_pos))
                        return FALSE;
        }

        return TRUE;
}

static gboolean at_least_one_condition_matched(
                const struct srd_decoder_inst *di, unsigned int num_conditions)
{
        unsigned int i;

        /* Caller ensures di != NULL. */

        for (i = 0; i < num_conditions; i++) {
                if (di->match_array->data[i])
                        return TRUE;
        }

        return FALSE;
}

static gboolean find_match(struct srd_decoder_inst *di)
{
        uint64_t i, j, num_samples_to_process;
        GSList *l, *cond;
        const uint8_t *sample_pos;
        unsigned int num_conditions;

        /* Caller ensures di != NULL. */

        /* Check whether the condition list is NULL/empty. */
        if (!di->condition_list) {
                srd_dbg("NULL/empty condition list, automatic match.");
                return TRUE;
        }

        /* Check whether we have any non-NULL conditions. */
        if (!have_non_null_conds(di)) {
                srd_dbg("Only NULL conditions in list, automatic match.");
                return TRUE;
        }

        num_samples_to_process = di->abs_end_samplenum - di->abs_cur_samplenum;
        num_conditions = g_slist_length(di->condition_list);

        /* di->match_array is NULL here. Create a new GArray. */
        di->match_array = g_array_sized_new(FALSE, TRUE, sizeof(gboolean), num_conditions);
        g_array_set_size(di->match_array, num_conditions);

        /* Sample 0: Set di->old_pins_array for SRD_INITIAL_PIN_SAME_AS_SAMPLE0 pins. */
        if (di->abs_cur_samplenum == 0)
                update_old_pins_array_initial_pins(di);

        for (i = 0; i < num_samples_to_process; i++, (di->abs_cur_samplenum)++) {

                sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);

                /* Check whether the current sample matches at least one of the conditions (logical OR). */
                /* IMPORTANT: We need to check all conditions, even if there was a match already! */
                for (l = di->condition_list, j = 0; l; l = l->next, j++) {
                        cond = l->data;
                        if (!cond)
                                continue;
                        /* All terms in 'cond' must match (logical AND). */
                        di->match_array->data[j] = all_terms_match(di, cond, sample_pos);
                }

                update_old_pins_array(di, sample_pos);

                /* If at least one condition matched we're done. */
                if (at_least_one_condition_matched(di, num_conditions))
                        return TRUE;
        }

        return FALSE;
}

/**
 * Process available samples and check if they match the defined conditions.
 *
 * This function returns if there is an error, or when a match is found, or
 * when all samples have been processed (whether a match was found or not).
 * This function immediately terminates when the decoder's wait() method
 * invocation shall get terminated.
 *
 * @param di The decoder instance to use. Must not be NULL.
 * @param found_match Will be set to TRUE if at least one condition matched,
 *                    FALSE otherwise. Must not be NULL.
 *
 * @retval SRD_OK No errors occured, see found_match for the result.
 * @retval SRD_ERR_ARG Invalid arguments.
 *
 * @private
 */
SRD_PRIV int process_samples_until_condition_match(struct srd_decoder_inst *di, gboolean *found_match)
{
        if (!di || !found_match)
                return SRD_ERR_ARG;

        *found_match = FALSE;
        if (di->want_wait_terminate)
                return SRD_OK;

        /* Check if any of the current condition(s) match. */
        while (TRUE) {
                /* Feed the (next chunk of the) buffer to find_match(). */
                *found_match = find_match(di);

                /* Did we handle all samples yet? */
                if (di->abs_cur_samplenum >= di->abs_end_samplenum) {
                        srd_dbg("Done, handled all samples (abs cur %" PRIu64
                                " / abs end %" PRIu64 ").",
                                di->abs_cur_samplenum, di->abs_end_samplenum);
                        return SRD_OK;
                }

                /* If we didn't find a match, continue looking. */
                if (!(*found_match))
                        continue;

                /* At least one condition matched, return. */
                return SRD_OK;
        }

        return SRD_OK;
}

/**
 * Worker thread (per PD-stack).
 *
 * @param data Pointer to the lowest-level PD's device instance.
 *             Must not be NULL.
 *
 * @return NULL if there was an error.
 */
static gpointer di_thread(gpointer data)
{
        PyObject *py_res;
        struct srd_decoder_inst *di;
        int wanted_term;
        PyGILState_STATE gstate;

        if (!data)
                return NULL;

        di = data;

        srd_dbg("%s: Starting thread routine for decoder.", di->inst_id);

        gstate = PyGILState_Ensure();

        /*
         * Call self.decode(). Only returns if the PD throws an exception.
         * "Regular" termination of the decode() method is not expected.
         */
        Py_INCREF(di->py_inst);
        srd_dbg("%s: Calling decode().", di->inst_id);
        py_res = PyObject_CallMethod(di->py_inst, "decode", NULL);
        srd_dbg("%s: decode() terminated.", di->inst_id);

        /*
         * Termination with an EOFError exception is accepted to simplify
         * the implementation of decoders and for backwards compatibility.
         */
        if (PyErr_Occurred() && PyErr_ExceptionMatches(PyExc_EOFError)) {
                srd_dbg("%s: ignoring EOFError during decode() execution.",
                        di->inst_id);
                PyErr_Clear();
                if (!py_res)
                        py_res = Py_None;
        }
        if (!py_res)
                di->decoder_state = SRD_ERR;

        /*
         * Make sure to unblock potentially pending srd_inst_decode()
         * calls in application threads after the decode() method might
         * have terminated, while it neither has processed sample data
         * nor has terminated upon request. This happens e.g. when "need
         * a samplerate to decode" exception is thrown.
         */
        g_mutex_lock(&di->data_mutex);
        wanted_term = di->want_wait_terminate;
        di->want_wait_terminate = TRUE;
        di->handled_all_samples = TRUE;
        g_cond_signal(&di->handled_all_samples_cond);
        g_mutex_unlock(&di->data_mutex);

        /*
         * Check for the termination cause of the decode() method.
         * Though this is mostly for information.
         */
        if (!py_res && wanted_term) {
                /*
                 * Silently ignore errors upon return from decode() calls
                 * when termination was requested. Terminate the thread
                 * which executed this instance's decode() logic.
                 */
                srd_dbg("%s: Thread done (!res, want_term).", di->inst_id);
                PyErr_Clear();
                PyGILState_Release(gstate);
                return NULL;
        }
        if (!py_res) {
                /*
                 * The decode() invocation terminated unexpectedly. Have
                 * the back trace printed, and terminate the thread which
                 * executed the decode() method.
                 */
                srd_dbg("%s: decode() terminated unrequested.", di->inst_id);
                srd_exception_catch("Protocol decoder instance %s: ", di->inst_id);
                srd_dbg("%s: Thread done (!res, !want_term).", di->inst_id);
                PyGILState_Release(gstate);
                return NULL;
        }

        /*
         * TODO: By design the decode() method is not supposed to terminate.
         * Nevertheless we have the thread joined, and srd backend calls to
         * decode() will re-start another thread transparently.
         */
        srd_dbg("%s: decode() terminated (req %d).", di->inst_id, wanted_term);
        Py_DECREF(py_res);
        PyErr_Clear();

        PyGILState_Release(gstate);

        srd_dbg("%s: Thread done (with res).", di->inst_id);

        return NULL;
}

/**
 * Decode a chunk of samples.
 *
 * The calls to this function must provide the samples that shall be
 * used by the protocol decoder
 *  - in the correct order ([...]5, 6, 4, 7, 8[...] is a bug),
 *  - starting from sample zero (2, 3, 4, 5, 6[...] is a bug),
 *  - consecutively, with no gaps (0, 1, 2, 4, 5[...] is a bug).
 *
 * The start- and end-sample numbers are absolute sample numbers (relative
 * to the start of the whole capture/file/stream), i.e. they are not relative
 * sample numbers within the chunk specified by 'inbuf' and 'inbuflen'.
 *
 * Correct example (4096 samples total, 4 chunks @ 1024 samples each):
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *   srd_inst_decode(di, 1024, 2048, inbuf, 1024, 1);
 *   srd_inst_decode(di, 2048, 3072, inbuf, 1024, 1);
 *   srd_inst_decode(di, 3072, 4096, inbuf, 1024, 1);
 *
 * The chunk size ('inbuflen') can be arbitrary and can differ between calls.
 *
 * Correct example (4096 samples total, 7 chunks @ various samples each):
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *   srd_inst_decode(di, 1024, 1124, inbuf,  100, 1);
 *   srd_inst_decode(di, 1124, 1424, inbuf,  300, 1);
 *   srd_inst_decode(di, 1424, 1643, inbuf,  219, 1);
 *   srd_inst_decode(di, 1643, 2048, inbuf,  405, 1);
 *   srd_inst_decode(di, 2048, 3072, inbuf, 1024, 1);
 *   srd_inst_decode(di, 3072, 4096, inbuf, 1024, 1);
 *
 * INCORRECT example (4096 samples total, 4 chunks @ 1024 samples each, but
 * the start- and end-samplenumbers are not absolute):
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
 *
 * @param di The decoder instance to call. Must not be NULL.
 * @param abs_start_samplenum The absolute starting sample number for the
 *              buffer's sample set, relative to the start of capture.
 * @param abs_end_samplenum The absolute ending sample number for the
 *              buffer's sample set, relative to the start of capture.
 * @param inbuf The buffer to decode. Must not be NULL.
 * @param inbuflen Length of the buffer. Must be > 0.
 * @param unitsize The number of bytes per sample. Must be > 0.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @private
 */
SRD_PRIV int srd_inst_decode(struct srd_decoder_inst *di,
                uint64_t abs_start_samplenum, uint64_t abs_end_samplenum,
                const uint8_t *inbuf, uint64_t inbuflen, uint64_t unitsize)
{
        /* Return an error upon unusable input. */
        if (!di) {
                srd_dbg("empty decoder instance");
                return SRD_ERR_ARG;
        }
        if (!inbuf) {
                srd_dbg("NULL buffer pointer");
                return SRD_ERR_ARG;
        }
        if (inbuflen == 0) {
                srd_dbg("empty buffer");
                return SRD_ERR_ARG;
        }
        if (unitsize == 0) {
                srd_dbg("unitsize 0");
                return SRD_ERR_ARG;
        }

        if (abs_start_samplenum != di->abs_cur_samplenum ||
            abs_end_samplenum < abs_start_samplenum) {
                srd_dbg("Incorrect sample numbers: start=%" PRIu64 ", cur=%"
                        PRIu64 ", end=%" PRIu64 ".", abs_start_samplenum,
                        di->abs_cur_samplenum, abs_end_samplenum);
                return SRD_ERR_ARG;
        }

        di->data_unitsize = unitsize;

        srd_dbg("Decoding: abs start sample %" PRIu64 ", abs end sample %"
                PRIu64 " (%" PRIu64 " samples, %" PRIu64 " bytes, unitsize = "
                "%d), instance %s.", abs_start_samplenum, abs_end_samplenum,
                abs_end_samplenum - abs_start_samplenum, inbuflen, di->data_unitsize,
                di->inst_id);

        /* If this is the first call, start the worker thread. */
        if (!di->thread_handle) {
                srd_dbg("No worker thread for this decoder stack "
                        "exists yet, creating one: %s.", di->inst_id);
                di->thread_handle = g_thread_new(di->inst_id,
                                                 di_thread, di);
        }

        /* Push the new sample chunk to the worker thread. */
        g_mutex_lock(&di->data_mutex);
        di->abs_start_samplenum = abs_start_samplenum;
        di->abs_end_samplenum = abs_end_samplenum;
        di->inbuf = inbuf;
        di->inbuflen = inbuflen;
        di->got_new_samples = TRUE;
        di->handled_all_samples = FALSE;

        /* Signal the thread that we have new data. */
        g_cond_signal(&di->got_new_samples_cond);
        g_mutex_unlock(&di->data_mutex);

        /* When all samples in this chunk were handled, return. */
        g_mutex_lock(&di->data_mutex);
        while (!di->handled_all_samples && !di->want_wait_terminate)
                g_cond_wait(&di->handled_all_samples_cond, &di->data_mutex);
        g_mutex_unlock(&di->data_mutex);

        /* Flush all PDs in the stack that can be flushed */
        srd_inst_flush(di);

        if (di->want_wait_terminate)
                return SRD_ERR_TERM_REQ;

        return SRD_OK;
}


/**
 * Flush all data that is pending, bottom decoder first up to the top of the stack.
 *
 * @param di The decoder instance to call. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @private
 */
SRD_PRIV int srd_inst_flush(struct srd_decoder_inst *di)
{
        PyGILState_STATE gstate;
        PyObject *py_ret;
        GSList *l;
        int ret;

        if (!di)
                return SRD_ERR_ARG;

        gstate = PyGILState_Ensure();
        if (PyObject_HasAttrString(di->py_inst, "flush")) {
                srd_dbg("Calling flush() of instance %s", di->inst_id);
                py_ret = PyObject_CallMethod(di->py_inst, "flush", NULL);
                Py_XDECREF(py_ret);
        }
        PyGILState_Release(gstate);

        /* Pass the "flush" request to all stacked decoders. */
        for (l = di->next_di; l; l = l->next) {
                ret = srd_inst_flush(l->data);
                if (ret != SRD_OK)
                        return ret;
        }

        return di->decoder_state;
}

/**
 * Communicate the end of the stream of sample data to a decoder instance.
 *
 * @param[in] di The decoder instance to call. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @private
 */
SRD_PRIV int srd_inst_send_eof(struct srd_decoder_inst *di)
{
        GSList *l;
        int ret;

        if (!di)
                return SRD_ERR_ARG;

        /*
         * Send EOF to the caller specified decoder instance. Only
         * communicate EOF to currently executing decoders. Never
         * started or previously finished is perfectly acceptable.
         */
        srd_dbg("End of sample data: instance %s.", di->inst_id);
        if (!di->thread_handle) {
                srd_dbg("No worker thread, nothing to do.");
                return SRD_OK;
        }

        /* Signal the thread about the EOF condition. */
        g_mutex_lock(&di->data_mutex);
        di->inbuf = NULL;
        di->inbuflen = 0;
        di->got_new_samples = TRUE;
        di->handled_all_samples = FALSE;
        di->want_wait_terminate = TRUE;
        di->communicate_eof = TRUE;
        g_cond_signal(&di->got_new_samples_cond);
        g_mutex_unlock(&di->data_mutex);

        /* Only return from here when the condition was handled. */
        g_mutex_lock(&di->data_mutex);
        while (!di->handled_all_samples && !di->want_wait_terminate)
                g_cond_wait(&di->handled_all_samples_cond, &di->data_mutex);
        g_mutex_unlock(&di->data_mutex);

        /* Flush the decoder instance which handled EOF. */
        srd_inst_flush(di);

        /* Pass EOF to all stacked decoders. */
        for (l = di->next_di; l; l = l->next) {
                ret = srd_inst_send_eof(l->data);
                if (ret != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Terminate current decoder work, prepare for re-use on new input data.
 *
 * Terminates all decoder operations in the specified decoder instance
 * and the instances stacked on top of it. Resets internal state such
 * that the previously constructed stack can process new input data that
 * is not related to previously processed input data. This avoids the
 * expensive and complex re-construction of decoder stacks.
 *
 * Callers are expected to follow up with start, metadata, and decode
 * calls like they would for newly constructed decoder stacks.
 *
 * @param di The decoder instance to call. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @private
 */
SRD_PRIV int srd_inst_terminate_reset(struct srd_decoder_inst *di)
{
        PyGILState_STATE gstate;
        PyObject *py_ret;
        GSList *l;
        int ret;

        if (!di)
                return SRD_ERR_ARG;

        /*
         * Request termination and wait for previously initiated
         * background operation to finish. Reset internal state, but
         * do not start releasing resources yet. This shall result in
         * decoders' state just like after creation. This block handles
         * the C language library side.
         */
        srd_dbg("Terminating instance %s", di->inst_id);
        srd_inst_join_decode_thread(di);
        srd_inst_reset_state(di);

        /*
         * Have the Python side's .reset() method executed (if the PD
         * implements it). It's assumed that .reset() assigns variables
         * very much like __init__() used to do in the past. Thus memory
         * that was allocated in previous calls gets released by Python
         * as it's not referenced any longer.
         */
        gstate = PyGILState_Ensure();
        if (PyObject_HasAttrString(di->py_inst, "reset")) {
                srd_dbg("Calling reset() of instance %s", di->inst_id);
                py_ret = PyObject_CallMethod(di->py_inst, "reset", NULL);
                Py_XDECREF(py_ret);
        }
        PyGILState_Release(gstate);

        /* Pass the "restart" request to all stacked decoders. */
        for (l = di->next_di; l; l = l->next) {
                ret = srd_inst_terminate_reset(l->data);
                if (ret != SRD_OK)
                        return ret;
        }

        return di->decoder_state;
}

/** @private */
SRD_PRIV void srd_inst_free(struct srd_decoder_inst *di)
{
        GSList *l;
        struct srd_pd_output *pdo;
        PyGILState_STATE gstate;

        srd_dbg("Freeing instance %s.", di->inst_id);

        srd_inst_join_decode_thread(di);

        srd_inst_reset_state(di);

        gstate = PyGILState_Ensure();
        Py_DECREF(di->py_inst);
        PyGILState_Release(gstate);

        g_free(di->inst_id);
        g_free(di->dec_channelmap);
        g_free(di->channel_samples);
        g_slist_free(di->next_di);
        for (l = di->pd_output; l; l = l->next) {
                pdo = l->data;
                g_free(pdo->proto_id);
                g_free(pdo);
        }
        g_slist_free(di->pd_output);
        g_free(di);
}

/** @private */
SRD_PRIV void srd_inst_free_all(struct srd_session *sess)
{
        if (!sess)
                return;

        g_slist_free_full(sess->di_list, (GDestroyNotify)srd_inst_free);
}

/** @} */